In silver halide light-sensitive color photographic materials (hereinafter may sometimes be called color light-sensitive materials(s)), as the magenta coupler for forming a magenta dye, 5-pyrazolone compounds have been widely used to date. A useful method for adding the magenta coupler to a photographic emulsion comprises introducing a oleophilic ballasting group into the coupler molecule, dissolving the ballasting group-introduced coupler into a high-boiling organic solvent, and then emulsifiedly dispersing the coupler solution into a hydrophilic colloid such as gelatin.
The essential nature required for the coupler is that the coupler shall
have a large solubility in high-boiling organic solvents;
have satisfactory dispersibility and dispersing stability and be hardly deposited in a silver halide emulsion;
be capable of forming a dye image which is so excellent in the spectral absorption characteristic as to provide a good tone, clear color image in a wide color reproducing region range;
provide a dye image which is resistant against light, heat and moisture; and
be producible at a good reproducibility from inexpensive raw materials in accordance with a simple synthesis method and yet at a high yield.
The ballasting group plays an important role for these characteristics, and includes those specific ballasting groups as described in Japanese Patent Examined Publication Nos. 3660/1969, 25655/1973, 25932/1973, 25934/1973, 16057/1974 and 40804/1976; Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 4481/1972, 8228/1974, 19435/1975, 126831/1976, 86333/1977, 30126/1981, 146251/1982, 42045/1983, 177557/1984 and 24547/1985; and U.S. Pat. Nos. 2,908,573, 2,920,961 and 3,227,544.
However, these ballasting groups are still insufficient to satisfy the above-mentioned characteristics. For example, as the ballasting group, the Japanese Patent Examined Publication No. 25934/1973 discloses 2-(3-dodecyloxyphenoxy)butylamido group (1); the Japanese Patent O.P.I. Publication No. 4481/1972 discloses 4,6-dicyclopentyl-3-methylphenoxy group (2); the Japanese Patent Examined Publication No. 3660/1969 discloses 2,4-di-sec-amylphenoxyacetamido group (3); the Japanese Patent O.P.I. Publication No. 86333/1977 discloses 4-nonylphenoxycarbonylethylamido group (4); the Japanese Patent O.P.I. Publication No. 177557/1984 discloses sulfamoylphenylenesulfonyl group (5); and the Japanese Patent Examined Publication No. 40804/1976 discloses 4-nonylphenoxyacetamido group (6). Those magenta couplers obtained by introducing the groups (1), (2), (4) and (6) out of the above-mentioned ballasting groups into 5-pyrazolone compounds all show excellent solubility in high-boiling organic solvents, but in the case of (1) and (4), the formed dyes' spectral absorption range is too broad, while in the case of (2) and (6), it is difficult to refine the produced couplers therefrom.
In the case of (3), the obtained coupler's solubility in high-boiling organic solvents is not deemed sufficient, while in (5), the obtained coupler is improved on its color formability but lacks solubility in high-boiling organic solvents.
Thus, development of such ballasting groups as to meet all the essential nature required for the foregoing couplers has been demanded.